Читать книгу Clinical Guide to Fish Medicine - Группа авторов - Страница 42

The ears of elasmobranchs are similar to other vertebrates and respond to acoustical, vibrational, and gravitational forces. They are located in cartilaginous otic capsules just caudal to the large optic capsules; the only external indication of their position is tiny paired endolymphatic pores (<1 mm diameter) on the dorsal chondrocranium near the medial line (Tester et al. 1972). Each ear has an inner ear labyrinth (utriculus, sacculus, and lagena) but none of the accessory organs seen in teleosts. Within the endolymphatic duct, instead of an otolith, there is an otoconial paste of calcium carbonate granules in gel that functions like the otoliths in teleosts (Mulligan and Gauldie 1989; Popper et al. 2005). Patches of sensory epithelium known as the macula neglecta are used for vibration detection in many species (Shuttleworth 2012). Audiograms show sharks hear frequencies from 50 to 1500 Hz with greatest sensitivity at 400–600 Hz (Popper 2000; Myrberg 2001). Clinicians should recognize sensitivity of elasmobranchs to pumps and filtration equipment that produce vibration and sound in enclosed spaces.